The present invention relates to a new washing process and a washing apparatus suitable to washing clothes, tableware, medical equipments and washing hands, etc.
Surfactant, such as chemicals and soup, have been heretofore been used for washing clothes, tableware, medical equipment, toilets, etc., however, there have been problems of causing chapping hands when washing, a safety issue on body by residual detergent on washing items, and residual harmful substances after a treatment of discharging water, etc.
Inventors of the present invention have proposed a so-called non-detergent washing method by using electrolyzed water as disinfectant detergent. It utilizes a protein removing effect of alkaline electrolytic water obtained by electrolyzing water comprising electrolyte and a disinfection effect of acid electrolytic water, which have been widely noticed as substitution of conventional chemicals and surfactant.
When applying such a kind of detergent to purposes of washing clothes and dishes, etc., it is on the assumption to have detergency comparable to or more excellent than the conventional detergent has. It is necessary, when designing detergent, to construct in terms of washing mechanism what kind of property should be a controlling factor.
It is also required to be harmless to human body even if a user takes it by mistake, to be safe not to cause chapped skin when touched by hands and to be easily handled.
Furthermore, it is required that the waste water containing the detergent after washing clothes and dishes, etc. excels in being easily handled able to be discharged as it is to the living environment without any special treatment, that is, excels in easy treatment of discharged water.
An object of the present invention is to provide a washing process and a washing apparatus having detergency comparable to or more excellent than that of a washing process using conventional detergent, being low at cost, excelling in safety, being easily handled, and thereby the waste water is easily treated.
The inventors of the present invention diligently studied washing mechanism and found that it was possible to obtain detergency comparable to detergent of the prior art, such as surfactant, or increased detergency by softening washing water, and with a cleanser effect and adsorptive effect of compositions produced at the time of softening the washing water. They also found that remarkable detergency was attained by softening a solution comprising alkali metal ion and carbonate ion and/or bicarbonate ion.
(1) Namely, a washing process of the present invention washes items to be washed simultaneously with softening washing water comprising alkali metal ion and at least one of carbonate ion and bicarbonate ion.
Also, the washing process of the present invention softens the washing water comprising alkali metal ion and at least one of carbonate ion and bicarbonate ion and washes items to be washed with the softened washing water.
Namely, a timing of softening the washing water comprising the above specified ions may be before washing or during washing. It is preferable to soften the water during washing.
Mainly, calcium ion Ca2+ and magnesium ion Mg2+ give a negative influence on detergency. In the present invention, since the washing water comprises at least one of carbonate ion CO32xe2x88x92 and bicarbonate ion HCO3xe2x88x92, calcium ion Ca2+ and magnesium ion Mg2+ bond with them and the existing ratio of the calcium ion Ca2+ and magnesium ion Mg2+ in the washing water becomes small. Therefore, the detergency is not decreased.
In addition to this, calcium carbonate CaCO3 or magnesium carbonate MgCO3 precipitated as a result of bonding calcium ion Ca2+ and magnesium ion Mg2+ with magnesium carbonate ion CO32xe2x88x92 physically removes dirt/stain by the cleansing effect and adsorption effect thereof, thus, contributes to increase the detergency.
Namely, the present invention is not simply a washing method using softened water nor to soften washing water, but also to generate compositions capable of physically removing dirt/stain simultaneously with softening the water.
Accordingly, when pouring the washing water comprising alkali metal ion and at least one of carbonate ion and bicarbonate ion together with washing items into the washing bath, calcium ion and magnesium ion contained in the washing water bond with the carbonate ion and bicarbonate ion to precipitate calcium carbonate and calcium bicarbonate. As a result, the washing water in the washing bath is softened and calcium carbonate, etc. having a cleansing effect and adsorption effect is generated at the same time.
(2) The alkali metal ion according to the present invention is obtained by making aqueous solution of alkali metal sodium. As the alkali metal ion, potassium salt, sodium salt, lithium salt, etc. are mentioned in terms of improving detergency. Especially, potassium salt and sodium salt are preferable for being inexpensive and easy to obtain and excelling in safety and treatment of waste water.
The carbonate ion according to the present invention is obtained by making an aqueous solution of alkali metal sodium carbonate, and the bicarbonate ion is obtained by making an aqueous solution alkali sodium bicarbonate. As the alkali metal sodium carbonate, for example, sodium carbonate [Na2 CO3], potassium carbonate [K2 CO3], lithium carbonate [Li2 CO3], etc. can be mentioned, and as the alkali metal sodium bicarbonate, for example, potassium hydrogencarbonate [KHCO3], sodium hydrogencarbonate [NaHCO3], etc. can be mentioned.
The solvent for dissolving the above alkali metal ion and at least one of carbonate ion and bicarbonate ion is not specifically limited, and a variety of waters, for example, tap water, well water, soft water, refined water, pure water, or mixed water of these, etc. can be used.
(3) In the present invention, the washing water before being softened has a pH of 8.5 to 12.0, preferably 9.5 to 11.0, more preferably 10.0 to 11.0. By setting the pH 8.5 or more (preferably 9.5 or more, more preferably 10.0 or more), it becomes preferable in terms of promoting to bond calcium ion and magnesium ion with carbonate ion and bicarbonate ion. By setting the pH 12.0 or less (preferably, 11.0 or less), it becomes preferable in terms of safety against chapped hands, etc. and treatment of waste water.
Furthermore, in the present invention, the concentration of alkali metal ion, that of carbonate ion, and/or that of bicarbonate ion in the washing water before being softened are preferably within predetermined ranges, and such concentrations of ions can be indirectly specified by an electric conductivity (EC). Namely, the electric conductivity EC of the washing water before being softened is preferably 50 mS/m or more, more preferably 100 mS/m or more, and most preferably 150 mS/m or more. By setting the electric conductivity at such a high range, sufficient concentration of ions can be secured for invalidating Ca2+ and 2+ in the aqueous solution by bonding them with CO32xe2x88x92 and HCO3xe2x88x92.
The washing water before being softened can be obtained by electrolyzing, for example, a sodium hydrogencarbonate solution. At this time, when using a water flowing type electrolyzing apparatus having a high generation performance, cathode electrolytic solution generated in a cathode chamber is preferably set to have a concentration able to be used as washing water as it is in terms of handling. While, when using a batch type electrolyzing apparatus having a low generation performance, it is preferable to generate electrolytic solution of a high concentration and to dilute the same for using in terms of reducing the generation costs. The solvent for diluting at this time is not specifically limited and easily obtainable tap water, etc. can be used.
(4) In the washing process of the present invention, the process of softening the washing water comprising alkali metal ion and at least one of carbonate ion and bicarbonate ion preferably includes a process of promoting to soften the washing water.
As such a process of promoting to soften water, a process of applying heat energy to the washing water to be softened, a process of physically stirring or airing the washing water to be softened, a process of securing time for water softening reaction by leaving the washing water to be softened still, etc. can be mentioned as examples.
By applying heat energy to the washing water, for example, by heating the washing water or generating the washing water under a high temperature state, an activity level of ions becomes high, the reaction of calcium ion and magnesium ion with carbonate ion and bicarbonate ion is promoted, and water softening is completed in a short period of time.
Also, when performing stirring or airing, a collision frequency between ions mechanically increases, so the reaction between magnesium ion and carbonate ion and/or bicarbonate ion is promoted and water softening is also completed in a short period of time by this.
Also, other than these forcible processes, a sufficient reaction time can be secured by leaving the washing water still and thereby water softening can be promoted, as well.
(5) The total hardness of the softened washing water is 35 ppm or less, preferably 15 ppm or less, more preferably 10 ppm or less. By setting the total hardness within this range, further increase of detergency can be expected.
(6) In the present invention, in order to reduce the total hardness in a short time to further increase the detergency, it is preferable to add coagulation agent or chelating agent to the above softened washing water having a reduced total hardness.
It is because, by adding the coagulation agent or chelating agent at this timing, the reduction of the total hardness can be attained in a short time. As the coagulation agent, for example, aluminum sodium sulfate (sodium alum), etc. can be mentioned, and as the chelating agent, EDTA, zeolite, etc. are mentioned as examples.
Also, in order to reduce the total hardness in a short time for further increased detergency, it is preferable to add fatty acid to the above softened washing water having a reduced total hardness. It is because, by adding fatty acid at this timing, reduction of the total hardness can be attained in a short time. As the fatty acid, oleic acid, etc. can be mentioned as an example. The same effect can be also obtained by adding soap.
A timing of adding the coagulation agent, chelating agent or fatty acid is not specifically limited, however, preferably, it is added when the total hardness of the washing water becomes 35 ppm or lees (preferably 15 ppm or less, more preferably 10 ppm or less).
(7) According to another viewpoint of the present invention, there is provided a washing apparatus including a means to wash items to be washed simultaneously with softening the washing water comprising alkali metal ion and at least one of carbonate ion and bicarbonate ion.
There is also provided a washing apparatus including a means to wash the washing items with the softened washing water after softening the washing water comprising alkali metal ion and at least one of carbonate ion and bicarbonate ion.
In this case, it is preferable to further include a means to promote to soften the above washing water.
It is also preferable to include a means to generate the above washing water before being softened by electrolyzing aqueous solution of sodium hydrogencarbonate.
It is also preferable to include a means to add coagulation agent or chelating agent after the total hardness of the above washing water to be softened becomes 35 ppm or less.
It is also preferable to include a means to add fatty acid after the total hardness of the above washing water to be softened becomes 35 ppm or less.
The above washing apparatus can be applied to a domestic or business purpose washer, dish washer, medical equipment washing apparatus, grease removing washer for processing machine, etc.